The Flemish-speakers, who may be among the hundred or so Belgians believed to have joined the fight against Syria’s government, are heard complaining that the knife is dull, according to a translation of the video.

The video emerges as EU ministers on Friday discussed the potential security threat posed by the hundreds of young Europeans fighting alongside rebels in Syria.

“They’re not all jihadists or terrorists,” said French Interior Minister Manuel Valls. “But we need to be very concrete in how we work together and we must do this operationally.”

It is relatively easy and cheap to reach Syria from Europe, with a bus ride from the Balkans for instance costing only around 100 euros.

A recent report by King’s College London has said up to 600 people from 14 European countries, including Austria, Britain, Germany, Spain and Sweden had taken part in the Syria conflict since it began in March 2011.

The largest single contingent was from Britain but based on population, the figures for Belgium, Ireland and the Netherlands were the most significant, with around 200 between them.